Recycling the Forest: Year 3

By Bruce Rottink, Volunteer Nature Guide and Retired Research Forester

 

The plants growing at Tryon Creek State Natural Area (TCSNA) require a supply of nutrients to stay healthy and keep growing.  An important part of supplying those nutrients is the decay of dead organic matter like leaves and branches.  This decay process releases the chemicals in the dead leaves and branches so those nutrients can be reused by plants that are still growing.

 

Study Procedure

To study this process, I collected leaves, branches or cone scales of several species of trees found at TCSNA in September 2014.  I only collected fresh materials which had recently fallen to the ground.  Within two days I placed these in wire mesh (screen) “envelopes” and fastened the envelopes to the ground with nails.  During the first part of the study I took photographs of the envelopes on a monthly or quarterly basis, but starting in September of 2016 I switched to once-a-year monitoring.  The results after one and two years have already been published in earlier Naturalist Notes.

The one-, two- and three-year end results are presented here.  While I had two envelopes for each of the materials, I only selected the most photogenic envelope for inclusion in this report.

 

Red Alder (Alnus rubra) Leaves

Red alder is a common tree at TCSNA, and is renowned for dropping its high nitrogen leaves onto the ground while they are still green.  The results from this study are seen in the photos below.

Photo 1

Left: Start (0 years). Right: After 1 year.

Photo 2

Left: After 2 years. Right: After 3 years.

 

One university research project studying the decay of dead red alder leaves indicated that 93% of the nitrogen in the alder leaves was released into the soil via the decay process the first year.  The same study found that 91% of the calcium and 97% of the potassium (both key nutrients) were also released during the first year of leaf decay1.  This relatively rapid decay of the red alder leaves was attributed to the fact that they generally contain higher levels of nutrients than most trees, thus nourishing the decay organisms.

 

Western Redcedar (Thuja plicata) Branchlets

Photo 3

Left: Start (0 years). Right: After 1 year.

 

Photo 4

Left: After 3 years. Right: After 3 years.

In sharp contrast to the red alder leaves, the western redcedar foliage contains lower levels of many nutrients, thus making it a somewhat less attractive food source for microorganisms.  In addition, redcedar foliage and twigs contain many terpenes.  Terpenes not only give the tree it’s distinctive “cedar smell,” but terpenes also have anti-fungal properties.  The major terpene in western redcedar (α-thujone ) is shown below.

 

Photo 5.jpg

Chemical structure of α-thujonecaption

 

No wonder that the cedar is decaying a little more slowly than some of the other samples.

 

Bigleaf Maple (Acer macrophyllum) Leaves

Photo 6

Left: Start (0 years). Right: After 1 year.

 

Photo 7

Left: After 2 years. Right: After 3 years.

 

With no special chemical defenses against fungi, and a fairly high nutrient content, the maple leaves are another fast decaying material.

 

Douglas-fir (Pseudotsuga menziesii) cone scales

These Douglas-fir cone scales were already lying on the ground at the time of collection.  The cones they came from had probably been chewed apart by a squirrel looking for the nutritious seeds.

 

Photo 8

Left: Start (0 years). Right: After 1 year.

Photo 9

Left: After 2 years. Right: After 3 years.

 

 

Superficially, the cone scales after three years look almost exactly like they did the day I put them in the bag.  Obviously the scales are made up of a very hard material, not too much different than the wood in the main stem of the tree.  Mother Nature made the cone scales very durable to protect the precious young seeds, and as a result, they are being recycled very slowly.

 

Douglas-fir branchlet

Photo 10

Left: Start ( 0 years). Right: After 1 year.

Photo 11

Left: After 2 years. Right: After 3 years.

 

Again, the Douglas-fir twigs and foliage contain some terpenes similar to the terpenes found in the redcedar, and thus, they decay more slowly than the alder and maple leaves.  Notwithstanding the resistance to decay, all the needles have fallen off the twigs.

 

The End Result

The nutrients within each of the samples used in this study will be released and then absorbed by living plants and fungus, helping the forest to grow the next generation of life.  This study shows the enormous differences in the decay times of different kinds of tree litter.  The softer materials, like the alder and maple leaves also have the highest nutrient content, and lowest concentration of anti-fungal chemicals.  But, as the old saying goes, “All in good time!”  All these nutrients will once again join living organisms, ensuring the continuation of TCSNA’s forest!

 

1Radwan, M. A., Constance A. Harrington and J. M. Kraft.  1984.  Litterfall and nutrient returns in red alder stands in western Washington.  Plant and Soil 79(3):343-351.

 

Advertisements

Spiders in the Forest

By Bruce Rottink, Volunteer Nature Guide and Retired Research Forester

 

Some of the smallest, but most important predators at Tryon Creek State Natural Area (TCSNA) are our spiders.  Spiders are the most voracious predators in the world, consuming far more prey than larger, more dramatic predators like owls and coyotes.  It was estimated by an eminent spider scientist that the all world’s spiders together each year consume a weight of insects greater than the weight of the human population of England.1

 

Spiders:  Voracious Predators

Spiders catch their prey in variety of ways, the most obvious being those that weave webs.  Just a brief look around TCSNA reveals that we are home to many different kinds of spiders and their webs.

 

The Orb Weavers

The most common and recognizable group of spiders are the orb-weaving spiders, named for the shape of their webs as seen below.  These webs are designed to help the spider catch flying insects for food.

 

Photo 1

An orb spider web along Old Main Trail on a dewy morning. Photo by Bruce Rottink

 

After weaving the orb web, the spider will most often wait upside down in the center of the web for some hapless insect to become stuck to, and entangled in, the web.  The thrashing motion of the insect trying to escape attracts the spider’s attention.  I have also observed a situation where a Douglas-fir needle fell into a web and got stuck.  The spider ran down and disentangled the needle and threw it down.  Unfortunately it got tangled again lower in the web.  The spider went down further, and repeated the process, this time the needle fell free of the web.  The spider then returned to the center of the cleaned up web to continue monitoring the action.

 

Photo 2

Spider in the center of the web awaiting a victim. Photo by Bruce Rottink

 

Once the victim is in the web, the spider will rush to the insect and inject it with poison to kill it.  Sometimes, as seen below, the spider will wrap up the insect for future use.

 

Photo 3

Spider wrapping up a captured critter. Photo by Bruce Rottink.

 

 

The Mat Weavers

A slightly less common type of spider is the “mat weaving” spider.  I was lucky enough to be in the park on a dewy February morning which highlighted one of the better examples of a “mat” web that I have ever seen.  It is a flat web suspended by strands from the overhanging branches.  This particular web measured about 3 inches across.  Typically, these mat webs are not sticky, and the spider is lurking very near and when an insect gets into the web, the spider rushes over and poisons it before it can escape.  These kinds of webs can also be found in the crevices of large tree trunks.

 

Photo 4

Web of a mat-weaving spider found along Old Main Trail on a dewy morning. Photo by Bruce Rottink

                                                                                                           

The Funnel Weavers

An even less common type of web is made by “funnel weaving” spiders.  The example below was found along the Middle Creek Trail.  While it may not be obvious in the photo, this really is a three dimensional funnel.  The spider typically waits near the bottom of the funnel.

                                                                                                           

Photo 5

Web of a funnel-weaving spider at Tryon Creek State Natural Area. Photo by Bruce Rottink.

 

The Dome Weavers

A fourth kind of web which you may occasionally encounter at TCSNA is the product of a dome-weaving spider.  Again, these webs are not inherently “sticky” and the spider will rush towards the insect which is trying to escape the web and inject poison into it.  The example shown below was near the Iron Mountain Trail, and was approximately 1 foot wide.

                                                                                                                           

Photo 6

Dome weaving spider near the Iron Mountain Trail. Red arrow and inset show actual spider. Photo by Bruce Rottink

 

Webless Spiders

While it is the large spiders and their webs that attract our attention, the population of “tiny” spiders is considerable.  Worldwide, more than half of all spider species are less than 2/10 of an inch long1.  The spider below was living in a shrub with no obvious spider web.  It is important to know that a significant number of spider species do not use webs to catch their prey.  This spider MAY be among them.

 

Photo 7

A tiny spider close-up. Photo by Bruce Rottink

 

Shy and Sexy Spiders

Spiders reproduce from eggs.  Spiders’ sexual encounters are frequently a one-time event for the males, not because of any spider-y sense of monogamy, but because the female will oftentimes eat the male immediately after mating.

 

In some species the female will create a protected place to lay her eggs.  Examples of this behavior can be seen by looking for folded leaves.  When you consider that one small spider was able to fold over this leaf and fasten it together, it is nothing short of amazing.  An example found along the Old Main Trail at TCSNA is shown below.

 

Photo 8

Left: Normal thimbleberry leaf. Right: Top view of thimbleberry leaf folded into a spider nest. Photos by Bruce Rottink

 

The underside of this folded leaf is shown below.  The white areas between the leaf edges are web strands which hold the structure in place.  I was able to see an adult spider inside of this “nest” but my attempts to get a good photo of her were not successful.

Photo 9

Underside of thimbleberry leaf folded into a spider nest (red arrow shows webbing). Photo by Bruce Rottink

 

A less dramatic, but still interesting example is shown below in which the mom spider just rolled up part of the leaf to create her nest.  She is still on guard.  The empty “skin” just to her left might either be the remnants of her nutritious sex partner, a recent meal or her own recently shed exoskeleton.  Just for scale, the brown thing she is standing on is a Douglas-fir needle.

 

Photo 10

Mom spider guarding her nest inside a folded leaf. Photo by Bruce Rottink

 

Gently unfolding this leaf just a bit revealed part of her nest, and also excited a few of the newly hatched young spiders into action.  The young spiders, one of which is highlighted with the red arrow in the photo below, started scurrying around as I unfolded the leaf, but none of them went very far.  After I looked, the leaf rolled up again quite nicely.

Photo 11

Inside of a rolled leaf is a spider’s nest and young spiders (red arrow). Photo by Bruce Rottink

 

The young spiders were almost unimaginably tiny.  They were way outside the range of what my camera was designed to photograph.  Some species of spiders are reported to eat plant material when they are young, and graduate to insect food as they mature.

 

Yeah for Spiders!

The spiders of TCSNA are a tremendous aid in controlling insect populations that could devour tons of plants and be much more annoying to our human visitors.  While they are a lot less visible and dramatic than other predators at the park, they are likely much more important, at least in the amount of insects they consume.  Next time you’re at the Park, pause for just a moment at a spider web, and thank the spider for all it does.

 

1Dalton, Stephen.  Spiders:  The Ultimate Predators.  Firefly Books Ltd.  2008

It’s Our Park, Let’s Keep It Clean!

By Bruce Rottink, Volunteer Nature Guide and Retired Research Forester

 

Tryon Creek State Natural Area (TCSNA) is a place which many critters love.  Some critters both love the park, and live in it.  These range from pileated woodpeckers (Dryocopus pileatus) to raccoons (Procyon lotor) and more.  Other creatures don’t live at the park, but they love to visit.  These other creatures include humans (Homo sapiens) and their pet dogs (Canis lupus familiaris).

 

As human beings, we’ve learned that we need to respect and take care of the park if we expect it to be here for future generations.  We’ve even figured out that to preserve the park as a place we actually want to come and visit, we need lavatories where we can deposit our feces and urine in the least environmentally disruptive manner.

Photo 1

Restroom entrance at Tryon Creek Nature Center

 

 

For our other major non-resident animal, dogs, we’ve got all the feces-related supplies visitors need, and a helpful reminder, at the entrances to the major trials, like you see here:

Photo 2

Doggie clean-up supplies

 

 

Good News

Based on several years of personal observation, the vast majority of humans who bring their dogs to the park are 101% responsible human beings, who clean up after their dogs.  I am happy to share the park with people and dogs like this.  One such person, whom I’ve chatted with many times, is pictured below!

 

Photo 3

Responsible dog owner with her pet & filled poop bag (red arrow).

 

 

And the good news is you don’t have to take it home with you because there are garbage cans on several of the trails near the Nature Center, like the one pictured below at the junction of Old Main Trail and Big Fir Trail:

Photo 4

A good place for dog poop!

 

 

But…

Sadly, there are what I believe to be a fairly small number of dog walkers who just don’t take the effort to clean up after their dog has a bowel movement.  If you need evidence, take a peek below (and this is just a small part of my collection of “dog poop” pictures.)

 

Photo 5

Fresh dog poop on the trail. (Can you see the flies in each picture?)

Photo 6

Moldy dog poop alongside the trail.

Photo 7

Bagged up dog poop, which doesn’t always get picked up on the way back! In fact, the little dirt splatters on the left bag suggest it’s been there since before the last rain storm.

Photo 8

Loaded up dog poop “scenically” located alongside the Middle Creek Trail.

 

The Downside of Dog Poop!

I sometimes come to the park primarily for a quiet walk where I can take in views of the beautiful woods.  When I see fresh, rotting or bagged dog poop all along, and sometimes on the trail, it really breaks the mood.

 

Aesthetics aside, dog poop in the park raises other issues.  Dog poop can be contaminated with eggs of parasitic roundworms (Toxocara spp.) or hookworms (Ancylostoma spp).  People can get these parasites by coming into contact with soil which has been contaminated by dog poop (reference:  Centers for Disease Control, Atlanta).

 

Several dog diseases are spread by dog poop as well.  These include Parvo virus, Giardia and Coccidia.  These diseases are commonly spread by dog poop.  If you walk your dog at TCSNA, don’t you want it to be safe from these feces-spread hazards?  Beyond that, TCSNA’s coyotes are also susceptible to the Parvo virus.

 

What are the alternatives?

Seriously folks, is leaving dog poop sitting around, bagged or unbagged, something you would do at your own home?  Tryon Creek is a State Natural Area.  You own this place.  But it is not just YOUR park, it is OUR park.   I, along with more than 4 million other Oregonians, also own a piece of this natural treasure!  Let’s work to keep our park clean.

 

As indicated above, dog poop bags are available at trailheads.  These are provide by Oregon State Parks for your use. There are garbage cans at most trailheads and a few major intersections for depositing your full dog poop bag.

 

To the vast majority of dog walkers who clean up after their animals:  Thank you for helping to keep TCSNA clean and safe.  I’m glad you and your dog have found your forest home here.

Drawn In

Art • Nature • Exploration

The NAI Blog

From the National Association for Interpretation

exploreportlandnature.wordpress.com/

Father/kids finding nature w/in the city

NAI Region 10

NAI R10 is a nonprofit professional organization serving NAI members in Alaska, Yukon, Alberta, British Columbia, Idaho, Washington and Oregon. Our mission is to inspire leadership and excellence to advance heritage interpretation as a profession.

Your Parks "Go Guide"

Oregon Parks and Recreation Department

Volunteer Voice

Oregon Parks and Recreation Department

Columbia River GORGEOUS

Ranger's blog for state parks in the Columbia River Gorge